In Japanese Patent Laid-opened No. Hei 2-56468, compounds represented by the following general formula [II]: ##STR2## wherein Z is alkylene containing 1 to 4 carbons and optionally substituted by alkyl, lower alkoxy, lower alkylthio lower alkyl, lower alkoxycarbonyl or benzyl, or a group represented by a general formula --C(r.sub.6) .dbd.C(r.sub.7)-- wherein r.sub.6 and r.sub.7 are each independently hydrogen, alkyl, lower alkoxy, lower alkylthio lower alkyl, lower alkoxycarbonyl or benzyl; r.sub.1 is lower alkyl optionally substituted by hydrogen or lower alkoxy, acetyl or lower alkenyl; r.sub.2 is hydrogen or methyl; r.sub.3 and r.sub.4 are each independently hydrogen, halogen, hydroxy, lower alkyl or lower alkoxy; r.sub.5 is lower alkyl optionally substituted by hydrogen or hydroxy; or r.sub.4 may form in together with r.sub.5 a bond, such as --CH.sub.2 --, --CH.sub.2 CH.sub.2 -- and --OCH.sub.2 --; and ---------- represents a single bond or a double bond, and pharmaceutically-compatible complexes thereof are disclosed, and wherein it is described that these compounds and complexes have (1) an excellent cardiotonic effect and therefore can be a therapeutic drug for congestive heart failure and (2) a preventive effect on platelet aggregation.